Healthy fats (you know, the kind found in avocados, olive oil, fish, coconut oil, and nuts) are essential to a balanced diet—and omega-3 fatty acids, a type of polyunsaturated fat we typically associate with salmon and fish oil supplements, are no exception.

There are three types of omega-3s we need: DHA (docosahexaenoic acid), EPA (eicosapentaenoic acid), and ALA (alpha linolenic acid). You can find DHA and EPA in animal sources, like fatty fish and grass-fed beef, and ALA in plant sources, like walnuts and flax seeds.

All three offer unique benefits, but research suggests DHA and EPA hold the most weight, particularly when it comes to your heart. That’s because they support a healthy blood pressure and help promote overall cardiovascular health, explains Melissa Majumdar, M.S., R.D., senior bariatric dietitian at the Brigham and Women’s Center for Metabolic and Bariatric Surgery.

Your ticker isn’t the only part of your body that benefits, though. Omega-3s are also essential to your brain and eye health, , since DHA is concentrated in the cells of your brain and retina, says Lauren Harris-Pincus, M.S., R.D.N., author of The Protein-Packed Breakfast Club. About 60 percent of our brain is actually made of fat! In fact, research from the American Academy of Neurology found that eating a diet high in omega-3s may be associated with lower levels of a blood protein related to age-related cognitive decline.

Related: You’ve Heard About Omega-3s—Here’s What You Should Know About Omega-6s

Sounds great, right? There’s just one problem: Our bodies can’t make nearly enough of the omega-3s we need, so we have to get them through our diet. (We can’t make ALA at all, and we’re not too great at making EPA and DHA.)

People can technically get their fill by eating the Dietary Guidelines for Americans‘ recommended eight ounces of fish (ideally omega-3 rich sources like salmon, tuna, herring, or sardines) per week—but data from the USDA shows that the average American falls short, eating just 2.7 ounces per week. Similarly, research published in Nutrients suggests that up to 96 percent of people don’t get enough DHA and EPA to protect their heart health.

While there’s no singular consensus on exactly how many omega-3s we need each day, most experts and organizations agree that between 250 and 500 milligrams of combined EPA and DHA a day is enough to boost our overall health. People with certain health conditions, though, may need more omega-3s than the average recommendations.

Pregnant and breastfeeding women, for instance, should really be aware of their consumption, since omega-3s are critical for prenatal development, says Majumdar. Pregnant women should aim for up to 12 ounces of fatty fish per week—or about 700 milligrams of omega-3s a day. Just avoid swordfish, shark, king mackerel, and tilefish, which have the highest risk of mercury contamination, and check in with your doctor before adding a supplement to your routine. (The Vitamin Shoppe brand’s Super Omega-3 Fish Oil contains 995 milligrams of total omega-3s.)

Omega-3s are also of extra concern for vegetarians and vegans (and anyone who can’t stand the taste of the sea). You see, plant-based ALA—like walnuts, chia seeds, and flaxseed oil—likely won’t be enough to meet your intake, since only two to 10 percent is converted to DHA and EPA. In this case, Amy Gorin, M.S., R.D.N., owner of Amy Gorin Nutrition, recommends a daily supplement that contains at least 250 milligrams of EPA and DHA. Algae-sourced omega-3 supplements—like Iwi’s Algae-Based Omega-3—are a great plant-based alternative to fish oil.

People with a family history of heart disease should also be aware of their intake, even at a younger age, since getting at least 500 milligrams of EPA and DHA daily helps promote overall heart health, says Gorin. And since those with diabetes are automatically at a higher risk of heart problems, they should also try to meet that minimum, says Majumdar.

If you turn to a fish oil supplement to help meet your needs, just check the Supplement Facts for specific EPA and DHA content. Some supplements may identify themselves as ‘500 milligrams,’ but contain less than half that amount of actual EPA and DHA, says Harris-Pincus. Double check the serving size, too, since some supplements require popping two pills instead of one.